1. The Field of the Invention
This invention relates generally to the field of optical switching devices for use in optical networks. In particular, embodiments of the present invention relate to a polarization based optical switch that is useful for switching optical signals in an optical networking environment.
2. The Relevant Technology
Fiber optics are increasingly used for transmitting voice and data signals. As a transmission medium, light provides a number of advantages over traditional electrical communication techniques. For example, light signals allow for extremely high transmission rates and very high bandwidth capabilities. Also, light signals are resistant to electromagnetic interference that would otherwise interfere with electrical signals. Light also provides a more secure signal because it does not emanate the type of high frequency components often experienced with conductor-based electrical signals. Light also can be conducted over greater distances without the signal loss typically associated with electrical signals on copper conductor.
Many conventional electrical networks are being upgraded to optical networks to take advantage of the increased speed and efficiency. One of the many required components of an optical network is an optical switching device. An optical switching device has the capability of switching an individual light signal between at least two different locations. Usually the optical signal is first demultiplexed or dispersed and the individual channels are switched and routed to specific locations. It is preferable to optically switch the optical signals rather than converting them to electrical signals and then switching them with conventional electrical switching techniques to maintain many of the advantages of optical networks.
The field of optical switching has progressed rapidly in the last decade. For large bandwidth applications, it is important that the optical switches be extremely small to allow many channels to be switched in a relatively small amount of space. One of the newest types optical switches fit into the general category of micro-electromechanical systems (MEMS). The size of these devices is typically on the order of microns. Three narrower categories of MEMS optical switches have emerged as the most promising design configurations: piezoelectric, electrostatic and electromagnetic. All of these switches utilize micro-mirrors to switch or reflect an optical channel or signal from one location to another depending on the relative angle of the micro-mirror. Therefore, the micro-mirror must be moved between at least two orientations. These movements must be extremely precise to properly route the optical signal to the desired location. Over time it is likely for the mirror to move into an improper orientation causing degradation or loss of the signal being switched. In addition, it is possible for debris to become lodged within the gap between the micro-mirror and the base and consequently interfere with the movement of the micro-mirrors thereby affecting the orientations of the micro-mirrors.
Due to increased bandwidth requirements on optical systems, optical switches are commonly arrayed to form devices that can switch many different channels. These arrayed switching devices are commonly used to add and drop individual signals from a dense wavelength division multiplexed (DWDM) signal. An array of switches is simply a large group of individual switches that are positioned or configured together to independently switch multiple channels. Since most optical switches contain moving parts, they tend to occupy unnecessarily large amounts of space in relation to the channels they are switching. Therefore, a large array of optical switches will generally require a relatively significant amount of precious space in an optical system. Certain types of optical switches do not lend themselves to being easily positioned together. For example, many MEMS based micro-mirror type switches cannot simply be stacked together or positioned adjacent to one another to form an arrayed switching device. These types of switches must be individually positioned in relation to one another to form an arrayed switching device.
Therefore, there is a need in the industry for an efficient optical switch that consumes low power, has no moving parts, is relatively small and is durable in relation to other optical switches.